replaced redis err check w/ verification of success string piped to log

root/scripts/backup.sh

@@ -580,9 +580,9 @@ checkExist fs "$sqlDumpDir/$sqlDumpFile"
 ### Save redis state
 echo -e "${op}${stamp} Saving redis state information...${normal}" >> "$logFile"
 docker-compose exec redis-mailcow redis-cli save >> "$logFile" 2>&1
-checkResult=$(docker-compose exec -T redis-mailcow echo "$?")
-# Verify save was successful
-if [ "$checkResult" = 0 ]; then
+## redis outputs a simple 'OK' if the export succeeded, so check the log file
+## for a line just written that says that specifically
+if [ $(tail -1 "$logFile") = "OK" ];
     echo -e "${ok}${stamp} -- [SUCCESS] redis state saved --${normal}" \
         >> "$logFile"
     else